# Midimuso on -12V **URL:** \ **Category:** DIY STUFF\ **Created:** [August 4, 2021, 8:48pm UTC](https://lookmumnocomputer.discourse.group/t/midimuso-on-12v/3849 "2021-08-04T20:48:38Z")\ **Posts on this page:** 1\ **Showing post:** 8
**Author:** ![fredrik](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/fredrik/32/682_2.png) [@fredrik](https://lookmumnocomputer.discourse.group/u/fredrik)\ **Post date:** [August 5, 2021, 4:10pm UTC](https://lookmumnocomputer.discourse.group/t/midimuso-on-12v/3849/8 "2021-08-05T16:10:04Z")
The original midimuso is broken by design; see discussion here: > [@Module requests](https://lookmumnocomputer.discourse.group/t/module-requests/39/166): > > Wait, they’re using an LM317 to produce 10.6 V from 12 V? That’s a bit optimistic: TL;DR the LM317 isn’t guaranteed to work with 12 V as used in that circuit, and odds are it’s not even regulating; you’re just seeing the supply voltage minus a collector-emitter voltage drop across the internal darlington transistor. You may get around it by trying different LM317s, but the only robust approach is to increase the supply voltage (which means changing the supply if the one you have is too good). In a quick test, I needed 12.25 V in to maintain regulation at 10.60 V out: > [@Module requests](https://lookmumnocomputer.discourse.group/t/module-requests/39/201): > > I have things to do, so I procrastinated a bit by measuring the dropout of one of [my LM317 supplies](https://lookmumnocomputer.discourse.group/t/mail-day-thread/101/174), with the output trimmed to 10.60 V at 15.00 V in, and then dropping the input step by step. The regulator gave up at around 12.25 V (so a 1.65 V drop): This was with a light load (~12 mA), and a divider consisting of 100 ohm + 2k trimmer (larger trimmers would exceed their power rating). I measured the resistances in circuit after trimming the voltage, and got 100.5 and 753.0; 100.5×1… but the exact drop depends on the current; the datasheet suggests a 3 V difference for the regulator to work properly across the full range. --- _[View the full topic](https://lookmumnocomputer.discourse.group/t/midimuso-on-12v/3849)._